1. Field of the Invention
The present invention relates generally to an independent suspension system for an automobile, and more particularly, to an independent suspension system with a leading lower control arm.
2. Description of the Related Art
Independent suspensions for conventional vehicles typically include a suspension system which has an upper control arm and a lower control arm attached to the wheel of the vehicle. As the vehicle is driven, the wheel bounces up and down in response to bumps in the road and during cornering. As this is going on, the travel of the wheel is controlled by both the upper and lower control arms as they pivot on axes which are nearly parallel to one another and with the center line of the vehicle. In conventional vehicles, the suspension system is attached to a drive shaft via a joint which can extend or retract as needed when the suspension moves. These joints may include splines, or other standard means of joining.
During the operation of the vehicle, the joint has to adjust in order to compensate for the distance that has been traveled by the wheel. Upon looking at the suspension mechanism from the rear of the vehicle, one can see that the upper and lower control arms essentially define a trapezoidal configuration. As the wheel flexes up and down in response to jounce and rebound, the trapezoid moves and creates a radius that pulls the joint back and forth, causing "halfshaft plunge". The distance that the joint moves, i.e, the "halfshaft plunge", is desirably kept to a minimum to add driveability and control of the vehicle.
In a front wheel drive car, there is generally a half shaft and a C-joint, the constant velocity joint. The half shaft extends from the transmission to the wheel. As the suspension moves, the halfshaft moves in and out to compensate for the radius which is created during the travel of the wheel. If the C-joint needs to move and become greatly displaced in order to compensate for the radius which is created, the C-joint itself can be put into a "weak" condition.
Minimizing the distance that the half shaft has to move is advantageous. In order to optimize roll understeer, anti-acceleration squat, and anti-brake lift, various configurations for the upper and lower control arms have been investigated in the past. Optimally, we want the halfshaft to move up and down directly without causing the C-joint to move in and out very much. This will stop the C-joint from traveling a great distance.
As an automobile is driven, the C-joint moves in and out, and it is desirable to minimize the travel from this in-and-out movement in order to give better stability to the suspension system. Furthermore, in normal operation of a vehicle, undesirable characteristics arise during weight transfer of the vehicle due to acceleration and braking. During acceleration, the rear of the vehicle "squats", while during braking, the rear of the vehicle "lifts". During a cornering operation, a combination of various vector forces cause an additional, more complicated set of problems. Therefore, it would be advantageous to optimize the geometry of the independent suspension system such that the vector forces and the wheel travel are optimized.
The imaginary steering point which is created by the geometry of the independent suspension system has been investigated by the present inventors, and has led them to the following invention.
Therefore, the present invention seeks to provide an independent suspension system having the advantage of allowing for an increased wheel travel without penalty to the drive train components by minimizing the in-and-out movement of the C-joint and thereby resulting in an improved ride without compromising the handling of the vehicle.